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Fix __attribute__((force_align_arg_pointer)) misalignment bug 

The force_align_arg_pointer attribute was using a hardcoded 16-byte
alignment value which in combination with -mstack-alignment=32 (or
larger) would produce a misaligned stack which could result in crashes
when accessing stack buffers using aligned AVX load/store instructions.

Fix the issue by using the "stackrealign" function attribute instead
of using a hardcoded 16-byte alignment.

Patch By: Gramner

Differential Revision: https://reviews.llvm.org/D45812

llvm-svn: 330331
This commit is contained in:
Erich Keane 2018-04-19 14:27:05 +00:00
parent 23bcf06a15
commit b127a39404
2 changed files with 7 additions and 22 deletions
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25
clang/lib/CodeGen/TargetInfo.cpp
View File

@ -1941,13 +1941,8 @@ void X86_32TargetCodeGenInfo::setTargetAttributes(
return;
if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) {
if (FD->hasAttr<X86ForceAlignArgPointerAttr>()) {
// Get the LLVM function.
llvm::Function *Fn = cast<llvm::Function>(GV);
// Now add the 'alignstack' attribute with a value of 16.
llvm::AttrBuilder B;
B.addStackAlignmentAttr(16);
Fn->addAttributes(llvm::AttributeList::FunctionIndex, B);
Fn->addFnAttr("stackrealign");
}
if (FD->hasAttr<AnyX86InterruptAttr>()) {
llvm::Function *Fn = cast<llvm::Function>(GV);
@ -2299,13 +2294,8 @@ public:
return;
if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) {
if (FD->hasAttr<X86ForceAlignArgPointerAttr>()) {
// Get the LLVM function.
auto *Fn = cast<llvm::Function>(GV);
// Now add the 'alignstack' attribute with a value of 16.
llvm::AttrBuilder B;
B.addStackAlignmentAttr(16);
Fn->addAttributes(llvm::AttributeList::FunctionIndex, B);
llvm::Function *Fn = cast<llvm::Function>(GV);
Fn->addFnAttr("stackrealign");
}
if (FD->hasAttr<AnyX86InterruptAttr>()) {
llvm::Function *Fn = cast<llvm::Function>(GV);
@ -2431,13 +2421,8 @@ void WinX86_64TargetCodeGenInfo::setTargetAttributes(
return;
if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) {
if (FD->hasAttr<X86ForceAlignArgPointerAttr>()) {
// Get the LLVM function.
auto *Fn = cast<llvm::Function>(GV);
// Now add the 'alignstack' attribute with a value of 16.
llvm::AttrBuilder B;
B.addStackAlignmentAttr(16);
Fn->addAttributes(llvm::AttributeList::FunctionIndex, B);
llvm::Function *Fn = cast<llvm::Function>(GV);
Fn->addFnAttr("stackrealign");
}
if (FD->hasAttr<AnyX86InterruptAttr>()) {
llvm::Function *Fn = cast<llvm::Function>(GV);

4
clang/test/CodeGen/function-attributes.c
View File

@ -71,7 +71,7 @@ void f15(void) {
// PR5254
// CHECK-LABEL: define void @f16
// CHECK: [[ALIGN:#[0-9]+]]
// CHECK: [[SR:#[0-9]+]]
// CHECK: {
void __attribute__((force_align_arg_pointer)) f16(void) {
}
@ -112,7 +112,7 @@ void f20(void) {
// CHECK: attributes [[NUW]] = { nounwind optsize{{.*}} }
// CHECK: attributes [[AI]] = { alwaysinline nounwind optsize{{.*}} }
// CHECK: attributes [[NUW_OS_RN]] = { nounwind optsize readnone{{.*}} }
// CHECK: attributes [[ALIGN]] = { nounwind optsize alignstack=16{{.*}} }
// CHECK: attributes [[SR]] = { nounwind optsize{{.*}} "stackrealign"{{.*}} }
// CHECK: attributes [[RT]] = { nounwind optsize returns_twice{{.*}} }
// CHECK: attributes [[NR]] = { noreturn optsize }
// CHECK: attributes [[NUW_RN]] = { nounwind optsize readnone }